The Norwegian Mother and Child Cohort Study (MoBa) is an ongoing prebirth cohort study. Enrollment was completed in 2008 resulting in 106,980 pregnancies in the study. The study is based on questionnaires completed by the mother and father, and biological specimens are collected from the mother, father and child. The main purpose of the study is to find causes of diseases. NIEHS is providing partial support for the study, and in 2002 expanded the data collection protocol to include collection of more biologic specimens from the mothers during the 17th week of pregnancy (additional serum, a specimen of whole blood collected in a trace-element free container, and urine). These specimens will enhance the ability to examine the relation of environmental exposures in relation to various health outcomes in the children and their mothers. As of April 30, 2009, 77,104 subjects had provided blood and urine that was collected in conjunction with NIEHS. In the past year, using the MoBa data, we have conducted a series of studies of health effects of in utero exposure to tobacco smoke. One report, on the association with miscarriage and stillbirth was published;no association was found. A second report, on the reproducibility of reported in utero exposure to tobacco smoke, was also published;the results show the reports of exposure are highly reproducible. We are now examining in utero exposure to tobacco smoke in relation to components of the metabolic syndrome and find evidence of an association. One manuscript reporting this finding has been revised and resubmitted to a journal, and a second manusecript is ready to be submitted after the first one is accepted. We added to the MoBa protocol the collection additional urine specimens in pregnancy, at weeks 23 and 29, for a subset of women. 690 women have a complete set of three urine specimens from pregnancy. We wrote a protocol to measure the levels of metabolites of organophosphate pesticides and bisphenol A in these specimens, to determine how reproducibile the levels are;the specimens are now being analyzed. This information will help us plan future studies on associations with health outcomes. We also have been studying perfluorinated alklys in relation to time-to-pregnancy and birthweight among women in the MoBa cohort. The association with increased time-to-pregnancy reported by others was also present in the MoBa data but appears to be due to an artifact of the study design;our manuscript on this has been revised and resubmitted to a journal. A manuscript on the association of perfluorinated compounds with birthweight also received favorable reviews from a journal and is being revised. We plan at least two other papers based on these data;one on values of clincial chemistry paramters in relation to perfluorinated compound levels, and one on determinants of blood levels. Because the study is in a relatively early phase, the number of scientific reports is still limited. At NIEHS, we are developing several studies that will be nested within MoBa. A list of the studies currently planed includes: Risk Factors for Cleft Lip and Palate, A Search for the Non-mendelian Transmission of Human Genes, Mother's Physical Activity During Pregnancy and Fetal Loss, Dietary Intake and Gestational Diabetes, Physical Activity in Pregnancy and Infant Neurodevelopment, Organophosphate Pesticide Exposure and Risk of Autism, and additional studies on perfluorinated compound exposure and health.